Effects of Channel Width Variations on Turbulent Flow Structures in the Presence of Three-Dimensional Pool-Riffle

Hadian, Sanaz; Afzalimehr, Hossein; Ahmad, Sajjad

doi:10.3390/su15107829

Cited by 3 publications

(2 citation statements)

References 31 publications

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“…In other words, the channel sidewalls and wall vegetation had a major role in producing turbulence eddies, and increased turbulence intensities. This finding was also reported in previous works conducted in channels with the varying channel width [29,38], as well as either submerged or emergent vegetation in channels [9,21,39].…”

Section: Turbulence Intensity Distributionsupporting

confidence: 89%

Incipient Motion of Bed Material in a Channel with Varying Width and Vegetated Channel Walls

Hadian,

Afzalimehr,

Sui

2023

Water

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This experimental study aims to investigate the characteristics of turbulent flow in channels with vegetated banks and varying channel width under the condition of the incipient motion of bed material. The natural reeds were used as emergent vegetation on the sidewalls of a laboratory flume. In total, nine experimental runs have been conducted with different experimental setups by using three different particle sizes of bed material and three different channel bed slopes. An Acoustic Doppler velocimetry (ADV) was used to acquire velocity components in three directions. The results of this study indicate that the streamwise velocities have the maximum and minimum values at the cross sections with the narrowest and widest width, respectively. When the aspect ratio is less than 5, the maximum velocity occurs below the water surface, due to presence of the secondary currents. It is found that, at all measurement points, the distribution of the Reynolds shear stress has a Z-shaped profile owing to presence of vegetation on the channel sidewalls. By extrapolating the profiles for flow velocity and Reynolds shear stress towards the surface of the channel bed, the near-bed incipient velocities and the corresponding shear stresses for the incipient motion have been determined. By increasing the channel bed slope, the estimated near-bed parameters for all particle sizes decreased, indicating the dominance of the gravity effect over the pressure gradient effect. It was also observed that the Shields method was invalid for assessing the incipient motion of bed material in the presence of vegetation on the sidewalls of a channel that has a varying width.

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Section: Turbulence Intensity Distributionsupporting

confidence: 89%

Incipient Motion of Bed Material in a Channel with Varying Width and Vegetated Channel Walls

Hadian,

Afzalimehr,

Sui

2023

Water

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“…Accordingly, any change in aspect ratio when it is less than 5 indicates similar patterns. Also, similar patterns are observed when the aspect ratio is larger than 5, indicating that it makes no difference to the velocity and Reynolds stress distributions if W/h is 2 or 4 [24].…”

Section: Introductionsupporting

confidence: 52%

Comparison of Velocity and Reynolds Stress Distributions in a Straight Rectangular Channel with Submerged and Emergent Vegetation

Mofrad,

Afzalimehr,

Parvizi

et al. 2023

Water

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Vegetation in rivers and streams plays an important role in preventing erosion and improving bank stability. Comparison between emergent vegetation (bank vegetation) and submerged vegetation, in terms of velocity and Reynolds stress distributions, for the same aspect ratio and flow discharge, has received limited attention in the literature. This study investigates the velocity and Reynolds stress, as well as the log law for submerged and emergent vegetation in a laboratory flume and compares the results for a different set up with different sediment size and aspect ratio but the same discharge. The results indicate that the influence of submerged vegetation on the secondary currents generation is less than emergent vegetation. In addition, the log law application is valid for both submerged and emergent vegetation cases, however, it is valid up to y/h = 0.75 for emergent vegetation (in which the vegetation cover in banks is partly out of the water) but up to y/h = 0.25 for vegetation bank. For both submerged and emergent vegetation, Reynolds stress distribution presents a convex form but with a different turning point. Comparison of the results with those in an artificial pool over submerged vegetation and low aspect ratio (<5) keeps almost the same form for velocity and Reynolds stress distributions but decreases the turning point in Reynolds stress distribution. For the submerged vegetation cover, the location of zero shear stress superposes that of maximum velocity, but for the emergent vegetation approaching the bank vegetation and shifting the maximum velocity towards the bed, the location of zero shear stress approaches the bed.

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Investigation of innovative designs of high-velocity channels for damping kinetic energy of flows

Rustem,

Yestaev,

Akhmetov

et al. 2024

Water Science &Amp; Technology

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In our contemporary world, demanding sustainable resource management, the study focuses on innovative fast flow channel designs. It investigates their efficacy in reducing flow kinetic energy, aiming to optimize water and energy management and diminish flood risks. Employing diverse methodologies, it analyzes and develops these designs, proving their substantial impact on stream energy management. These innovations not only enhance energy efficiency but also mitigate risks associated with excess kinetic energy, promoting safer stream management. This research significantly contributes to fluid dynamics and engineering, deepening the understanding of kinetic energy control in flows and offering potential solutions for water supply, environmental sustainability, and infrastructure safety challenges.

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Effects of Channel Width Variations on Turbulent Flow Structures in the Presence of Three-Dimensional Pool-Riffle

Cited by 3 publications

References 31 publications

Incipient Motion of Bed Material in a Channel with Varying Width and Vegetated Channel Walls

Incipient Motion of Bed Material in a Channel with Varying Width and Vegetated Channel Walls

Comparison of Velocity and Reynolds Stress Distributions in a Straight Rectangular Channel with Submerged and Emergent Vegetation

Investigation of innovative designs of high-velocity channels for damping kinetic energy of flows

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